There are some things you don’t know until you become pregnant with your first child: That you can see your baby’s heartbeat in an ultrasound long before it can be heard. That the twitch in your side is the beginning of a kick. That some people think it’s a good idea to eat your own placenta after the birth.

Yes, that last one seems to surprise many mothers.

I first came across the idea of placentophagia, as it is known, during one of my prenatal group sessions at the Family Health and Birth Center in Washington. While discussing things we might address in our birth plans, one of the midwives brought up the option of keeping our placentas.

“But why?” we all wanted to know.

Indeed, that is the question.

In some cultures, people bury the placenta and later plant a tree over it to honor new life. Other mothers make prints of the placenta, either with its blood or with colored paint, as keepsakes.

Then there are those who believe that the placenta’s nutritional value can benefit the new mother after childbirth.

There is a certain logic to the placenta’s being the perfect postpartum superfood. Throughout pregnancy, the organ transports blood, oxygen and nutrients from the mother to the baby. Some call it “the tree of life,” both for its many branching veins and its life-sustaining force.

The most commonly cited benefit of placenta consumption is that it helps balance hormones and thereby combats postpartum depression. Some also claim that it boosts milk production, helps the uterus contract and replenishes lost nutrients after childbirth. Web sites suggest using it in recipes like any other organ meat, pan frying it or cooking it in lasagna. Some strong-stomached mothers have used it raw in smoothies.

If all this sounds a bit too cannibalistic, there are “placenta encapsulation specialists,” often midwives or doulas, who transform the placenta from its messy postpartum condition into neat, sometimes even flavored, pills. “Mad Men” actress January Jones told People magazine that she began taking placenta pills after giving birth last fall and credits them with helping her to bounce back quickly. “It’s not witchcrafty or anything! I suggest it to all moms,” she told the magazine. “Your placenta gets dehydrated and made into vitamins. It’s something I was very hesitant about,” but she ended up taking the pills daily.

Hospitals consider the placenta biohazardous waste and dispose of it as such unless an arrangement to keep it is worked out beforehand. Sibley Memorial Hospital in the District of Columbia, for instance, provides a protective container in which to store the placenta if a mother asks. But with 3,500 births a year on average, the hospital has only had only two mothers make such a request in the last year and a half, hospital officials said.

Doula Tabare Depaep is a placenta lady. She works out of her Annapolis, Md., kitchen, and said a placenta feels “like a big rump roast.” She doesn’t find it any worse than handling meat. (Depaep is a vegetarian.) “I actually feel warmer toward the placenta because it grew a baby,” she said.

Many proponents of placenta consumption trace the practice to Chinese herbal medicine, where it is known as zi he che. One of the traditional preparations involves dehydrating the organ and then grinding it into a powder, which is basically what placenta encapsulation specialists do. Growing up in a Chinese family, I can recall taking sheep placenta pills once on the advice of my father, who practiced acupuncture. I just assumed it was for general health and well-being, like many of the herbal concoctions I grew up taking (sometimes believing it was better not to know the ingredients).

Scientists, however, tend to be skeptical about the benefits of placentophagia to humans.

“Most of the assumptions (about human placenta consumption) come from extrapolations from animal work, anecdotes and suppositions. But none of it comes from scientific data,” said Mark Kristal, a behavioral neuroscientist at the State University of New York at Buffalo who researches placentophagia in animals. (Humans are among the few mammals that don’t routinely eat their own placentas.)

The main benefit of the practice for animals, Kristal said, is that substances in the afterbirth appear to enhance pain relief during delivery, especially in the case of multiple births. (Amniotic fluid, available early in labor, also helps in pain relief.) But Kristal points out that cooking the placenta would destroy some of the beneficial aspects of the protein in the placenta, and that any positive outcomes mothers experience are likely to be a result of the placebo effect.

Part of the reason why there are no scientific data on the matter, Kristal explained, is that it is difficult to find women who haven’t already formed an opinion about the matter which would affect their perception. And even if the practice is found to have benefits, Kristal believes it would be better to analyze the healthful components of the placenta and then synthesize them into pharmacological products rather than eat the unprocessed organ.

“Periodically you get this back-to-nature feeling. People say, ‘Animals do it; we’re animals, so it’s got to be good for you.’ Well, animals do a lot of things we don’t do; not all of them would be good for us.”

“Personally, I don’t think moms are drawn to this because of scientific research,” said Depaep. “This helps them feel they’ve done something to avoid the baby blues and to help milk production. Part of (avoiding) postpartum depression is that it requires vigilance. I think moms like to know they’ve done what they can about it instead of feeling helpless.”

Depaep said the number of women wanting placenta encapulation services is on the rise, with about 20 percent of her clients of late asking for it as opposed to about 10 percent who maybe were interested it a few years ago. “It’s still a small number, but it’s growing,” she said.

Amanda Baerwaldt, a Frederick, Md., mother, wasn’t worried about the lack of evidence when she opted to have her placenta encapsulated after giving birth a few months ago.

“I wanted to avoid the baby blues if I could, and I wanted to stay away from conventional medicine,” she said. She felt joyful after giving birth, but a few days later, the what-ifs began to flood her. She started taking her placenta pills, and within 24 to 48 hours she felt better. “I felt a lot of energy,” she said, “like Wonder Woman. If I took it at 5 p.m. I couldn’t sleep all night.”

“Even if it is a placebo effect,” she added, “it still works. It’s the perfect balance for just you. You can freeze the pills, and they’ll last even up to menopause.”

I spent an entire childhood eating such Chinese delicacies as duck tongue, pigs’ blood and chicken feet, so most strange foods do not faze me. But I have to admit I felt queasy looking at those placenta recipes online, and I just wasn’t enthusiastic enough to spend money on encapsulation.